Environmental risk, perceived mortality risk, and facultative adjustment of life history strategy among young adults in the United States

1Department of Anthropology, Northwestern University, 2Cells to Society: The Center on Social Disparities and Health, Institute for Policy Research, Northwestern University, 3Human Development and Social Policy Program, Northwestern University

Mortality risk is key to defining life history tradeoffs, including allocations of effort to growth, reproduction, and maintenance, and the scheduling of important life history events such as age at maturity. In affluent, industrialized settings like the contemporary United States, energetic constraints are minimal and exogenous mortality risk is very low by historical standards. However, psychosocial stressors in infancy and childhood may still signal “risk” and influence life history strategies. We investigate this possibility using data from a large, nationally representative cohort study of young adults in the U.S., with the latest wave of data collected when participants were 24 to 32 years old (n>15,000). We use a series of regression models to investigate early psychosocial stressors as predictors of age at menarche for females, and patterns of reproductive activity for females and males. We also investigate indicators of investments in growth (height, weight) and maintenance (cell mediated immune function, health behaviors) as outcome variables. Lastly, we consider perceived mortality risk as a cognitive mechanism that may mediate associations with “risky” early environments. Analyses indicate the following: 1) adversity in childhood predicts earlier and more intensive reproductive effort; 2) adversity is associated with higher perceived mortality risk; and 3) higher perceived mortality risk predicts increased reproductive effort and reduced maintenance effort, as defined by health behaviors that protect against diseases of aging. These results highlight the utility of an integrated life history framework for understanding the long-term impact of psychosocial stressors early in development.

Supported by grant number R01HD053731 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development